1. Field of the Invention
This invention relates to a method of stabilizing acid aqueous solutions of hydrogen peroxide which are used in chemically solubilizing treatments such as pickling, etching and chemical polishing of copper and copper alloys. More particularly, it is an object of this invention to add glycol ethers to acid aqueous solutions of hydrogen peroxide which are unstable in the presence of copper ions to inhibit decomposition of the hydrogen peroxide for achievement of its economical use.
2. Description of the Prior Art
Chemcially dissolving treatments such as pickling which is removal by dissolving of oxidation scales on the surface of metallic materials, etching which is removal by dissolving of a portion of metallic phase and chemical polishing which is a polish treatment of the surface, are utilized in a wide area of industrial fields involving metallic materials.
Acid aqueous solutions of hydrogen peroxide are known to possess high solubilizing powers as chemically solubilizing agents for copper and copper alloy materials. On the other hand, hydrogen peroxide is a readily decomposable compound which is catalytically decomposed especially in the presence of copper ion. Consequently, it is economically disadvantageous that when an acid aqueous solution of hydrogen peroxide is employed in a chemically solubilizing treatment of copper and copper alloys, the copper is dissolved and accumulated in the solution to accelerate decomposition of the hydrogen peroxide, thereby considerably lowering the ratio of effective utilization of hydrogen peroxide.
Typical solutions among the acid aqueous solution for use in the chemically solubilizing treatment of copper and copper alloys contain 10-150 g./l. of hydrogen peroxide and 10- 200 g./l. of sulfuric acid. These solutions have been critically defective in practical uses in that, whereas they are stable in the absence of copper ion therein, the hydrogen peroxide will be rapidly decomposed or disappear in the presence of copper ions accumulated in the solutions.
Improvements heretofore known for reducing the decomposition of hydrogen peroxide include adding as a stabilizer saturated aliphatic alcohols, phenols, proteins, polymethylene polyamines and the like to the said aqueous solution of hydrogen peroxide. But, stabilizers having better stabilizing property have been desired.